The EyeTect®
Tremor Monitor Unit (the “TMU”) is currently in the
prototype stage but has already received FDA clearance (see
Appendix A) as a Class II medical device that directly
monitors brainstem activity by measuring Ocular Microtremor
(“OMT”).
OMT is a
high frequency, low amplitude tremor of the eyes triggered
by impulses originating in the oculomotor area of the
brainstem. The oculomotor neurons are embedded in the
reticular activating system, which is a group of nerve
pathways concerned with the level of consciousness from the
states of sleep, drowsiness, and relaxation to full
alertness and attention. These reticular groups of small
and large neurons have crossing, ascending and descending
fibers that connect with pathways in the brainstem and
spinal cord. Signals projecting upward through these
pathways cause a tonic vibration of the muscles attached to
the eye, thus creating micro-motion that is unnoticeable,
yet present in all individuals, even when the eyes are at
rest.
OMT is the
highest in frequency and lowest in amplitude of all
physiological tremors. Studies have concluded that the mean
frequency of OMT in normal healthy humans is 84 Hz (+/- 6
Hz) with a mean amplitude of six seconds of arc.
Normal OMT
consists of an irregular baseline with superimposed regular
sinusoidal episodes of activity called bursts. It has been
demonstrated that OMT’s frequency and amplitude vary
depending upon the patient state.
This graph
on the next page shows how OMT signals vary for normal,
sedated, and brain dead patients.
Chart: OMT
waveform for normal, sedated, and brainstem dead patients
OMT’s behavior has been studied for over seventy years.
Researchers, including the world’s foremost expert, Ciaran
Bolger, Ph.D., FRCS, FRCSI, have demonstrated its clinical
relevance in monitoring anesthesia, coma, brainstem death,
Parkinson’s disease, Multiple Sclerosis, and sleep
disorders. The initial studies were performed using an
open-eye sensor for very short periods of time and utilizing
post experiment signal analysis, neither of which is
practical from a clinical perspective.
In 2000,
Dr. Bolger and a group of neurosurgeons, engineers, and
business leaders formed EyeTect, LLC to develop a real-time,
closed-eye OMT monitoring system – the TMU – that is more
clinically useful and user-friendly than the open-eye
device.
EyeTect’s TMU has been proven effective in clinical studies,
and has received 510(k) clearance from the USFDA for use in
the OR and ICU (See Appendix A), as well as patent
protection from the USPTO.
The EyeTect®
TMU system provides an easy-to-use method of measuring OMT
through a closed eyelid and displaying the measurements in
real time on a standard patient monitor or a freestanding
monitor. A small sensor is placed on the patient’s closed
eyelid that picks up the micro-movement through the eyelid.
The OMT frequency, amplitude, waveform, and trend over time
are then instantaneously displayed on the TMU or bedside
monitor.
EyeTect will devote the next 18 months to refining and
packaging the TMU so that at the time of commercialization,
it will consist of (1) a computer interface card (similar to
a notebook computer wireless adapter) that will be
incorporated into the overhead or bedside monitor, along
with (2) a disposable sensor that is adhered to the closed
eyelid of the patient and connected via a thin cable back to
the interface card within the bedside monitor. This change
gives clinicians easy access to the patient’s OMT continuous
data via the standard bedside monitor.
